While much human diversity arose through genetic drift, it is increasingly clear that different human populations have distinctly adapted to the environments they encountered in the 100,000 years since our species left its east African birthplace. Today, some of these genetic adaptations account for inherent inter-individual differences in disease risk through different phenotypic response to identical environmental conditions. Here I propose to better understand this phenomenon by studying the separate adaptations to different temperatures that have occurred in the model species Drosophila melanogaster since it also left its African home and spread across the planet. In particular, I wil study how temperature affects developmental timing, a quantitative polygenic trait, and how different D. melanogaster populations have adapted to mitigate temperature's effects on development. PUBLIC HEALTH RELEVANCE: Difficulties in predicting the behavior of polygenic syndromes in a diverse population are confounded when myriad environmental influences affect the outcome. By using a similarly diverse wild sampling of the fruit fly Drosophila melanogaster that have adapted to a variety of specific ecosystems, I will explore the effect of a single environmental variable, temperature, on the growth of fly embryos. By understanding how different populations of flies with different genetics respond to changing temperatures, I will gai insight on how the genes of different people may react to health risks in the world around them.